1. Field of the Invention
The present invention relates to a headrest.
2. Description of the Related Art
A headrest which is called as an active headrest is configured such that a lock mechanism is unlocked when a vehicle is crashed from behind, and a link mechanism operates along with unlocking operation, whereupon the support plate springs out to receive the back of a passenger's head. Some active headrests have a return prevention mechanism which prevents or regulates, by means of a stopper, the support plate from returning to its initial position achieved before springing out, by a load imposed by the back of the passenger's head in the course of springing out of the support plate. By virtue of this mechanism, the support plate can be held at a position near the back of the passenger's head; and therefore, the back of the passenger's head can be reliably received.
JP-A-2007-106384 or U.S. Pat. No. 7,517,015 describes a related-art active headrest.
However, in the above-described headrest, when performing operation for returning the thus sprung out support plate to its initial position, the support plate cannot be returned to its initial position unless the regulation by the stopper is kept in a releasing state. Specifically, when performing the retuning operation, the operator has to return the support plate to its initial position by one hand while holding the stopper in the releasing state by the other hand. Since the operation requires both hands simultaneously, the operability of this returning operation is poor.